Manufacture of paper



United States Patent 3,429,772 MANUFACTURE OF PAlER Roland Michael Harvey, Leicester, and Christopher Richard Napier Johnson, Braintree, England, assignors to Chernstrand Limited, London, England No Drawing. Filed June 1, 1965, Ser. No. 460,534 Ciairns priority, application Great Britain, June 3, 1964,

23,014/64 US. Cl. 162-157 9 Claims int. (Cl. [021th /20 ABSTRACT OF THE DISCLOSURE By treatment with oxygen-forming agents, fibres formed from acrylonitrile polymers containing at least 80 percent by weight acrylonitrile spilt into sub-deniers requiring less beating than untreated fibres and when formed into paper sheets by conventional papermaking methods exhibit enhanced physical properties as tear and bursting strengths. Preferable oxygen-forming agents are potassium permanganate or ammonium persulphate.

This invention relates to the manufacture of paper formed from acrylonitrile polymer fibres. It is an object of the invention to increase the ease with which such fibres can be beaten, to provide a paper-making stock, in a conventional beater, refiner or stockmaker and to enable a paper to be produced having improved physical properties.

According to one aspect of the present invention there is provided a process for the treatment of fibres formed of an acrylonitrile polymer containing at least 80 percent by weight of acrylonitrile to render said fibres suitable for use in the manufacture of paper, comprising the steps of reducing said fibres to staple lengths, immersing said fibres in an aqueous solution of an oxygen-forming agent at a temperature in the range of from 10 C. to 100 C. for a predetermined period, thereby to partially disrupt said fibres, washing said fibres to remove said oxygenforming agent and drying said fibres. The invention also includes fibres when treated by such process.

According to another aspect of the invention there is provided a process for the manufacture of paper from fibres produced from an acrylonitrile polymer containing at least 80 percent by weight of acrylonitrile, comprising the steps of reducing said fibres to staple lengths, immersing said fibres in an aqueous solution of an oxygen-forming agent at a temperature in the range of from 10 C. to 100 C. for a predetermined period, thereby to partially disrupt said fibres, washing said fibres to remove said oxygen-forming agent, drying said fibres, beating said fibres in an aqueous dispersion and forming said fibres into a paper sheet or web. The invention also includes paper when produced by such process.

Preferably the oxygen-forming agents employed in carrying out the invention are potassium permanganate, or ammonium persulphate. Other agents which may be employed are sodium hypochlorite, sodium perborate, potassium bichromate and potassium persulphate. Other oxygen-forming agents that may be found suitable can be employed, including mixtures of any of the said agents.

It has been found that fibres which have been subjected to treatment in an aqueous solution of an oxygen-forming agent in accordance with the invention are partially disrupted and, when subjected to heating, are split into subdeniers therefore require a lesser amount of beating than fibres which have not been treated in the manner referred to. When the fibres treated in accordance with the invention are formed into paper webs or sheets by conventional paper-making methods they exhibit enhanced physical properties, notably as regards tear and bursting strengths.

Too

The fibres treated by the invention can be prepared from polyacrylonitrile, copolymers, including binary and ternary polymers containing at least percent by weight of acrylonitrile in the polymer molecule or a blend comprising polyacrylonitrile or copolymers comprising acrylonitrile With 2 to 50 percent by weight of the blend of another polymeric material, the blend having an overall polymerized acrylonitrile content of at least 80 percent by weight. For example, the polymer from which the fibres are prepared may be a copolymer of from 80 to 98 percent by weight of acrylonitrile and from 2 to 20 per cent by weight of another monomer containing C=C linkage and copolymerizable with acrylonitrile. Suitable copolymerizable mono-olefinic monomers include acrylic, alpha-chloroacrylic and methacrylic acids, the methacrylates, such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, methoxymethyl methacrylate, betachloroethyl methacrylate, and the corresponding esters of acrylic and alpha-chloroacrylic acids; vinyl chloride, vinyl fluoride, vinyl bromide, vinylidene chloride, l-chloro-lbromoethylene; methacrylonitrile; acrylamide and methacrylamide; alpha-chloroacrylamide, or monoalkyl substitution products thereof; methyl vinyl ketone; vinyl carboxylates, such as vinyl acetate, vinyl chloroacetate, vinyl propionate, and vinyl stearate; N-vinylimides, suchas N- vinylpthalimide and Nvinyl-succinimide; methylene malonic esters; itaconic acid and itaconic esters; N-vinylcarbazole; vinyl furane; alkyl vinyl ethers; vinyl sulphonic acid; ethylene alpha, beta-dicarboxylic acids or their anhydrides or derivatives, such as diethyl citraconate and diethyl mesaconate, styrene, vinyl napthalene, vinyl-substituted tertiary teterocyclic amines, such as the vinylpyridines and alkyl-substituted vinylpyridines, for example, Z-Vinylpyridine, 4-vinylpyridine and 2-methyl-5-vinyl pyridine; l-vinylimidazole and alkyl substituted l-vinylimidazoles, such as 2,4,5-methyl-l-vinylimidazole, vinyl pyrrolidone or vinyl piperlidone.

The polymer can be a ternary polymer or higher interpolymer, for example products obtained from the interpolymerization of acrylonitrile and two or more of any of the monomers, other than acrylonitrile enumerated above. More specifically, and preferably the ternary polymer comprises acrylontirile, methacrylonitrile and 2- vinylpyridine. The ternary polymers preferably contain from 80 to 98 percent by Weight of acrylonitrile, from 1 to 10 percent by weight of a vinylpyridine or a 1-vinyl imidazole, and from 1 to 18 percent by weight of another copolymerizable mono-olefinic substance, such as methacrylonitrile or vinyl chloride.

The polymer can also be a blend of a polyacrylonitrile or of a binary interpolymer of from 80 to 98 percent by weight of acrylonitrile and from 1 to 20 percent by weight of at least one other C:C contianing substance with from 2 to 50 percent of the weight of the blend of a copolymer of from 10 to 70 percent by weight of acrylonitrile and from 30 to percent by weight of at least one other C=C containing polymerizable monomer. Preferably, when the polymeric material comprises a blend it will be a blend of a terpolymer of 90 to 98 percent by weight of acrylonitrile and from 2 to 10 percent by weight of another mono-olefinic monomer, such as a vinyl acetate, which is not receptive to dyestuif, with a sufiicient amount of a copolymer of from 10 to 70 percent by weight of acrylonitrile and from 30 to 90 percent by weight of a vinyl-substituted tertiary heterocyclic amine, such as a vinylpyridine or l-vinylimidazole, to give a dyeable blend having an overall vinyl-substituted tertiary heterocyclic amine content of from 2 to 10 percent, based on the weight of the blend.

For a better understanding of the invention the following examples are given in which all percentages are by weight unless otherwise stated.

Example I In this example 100 grams dry weight undried acrylonitrile polymer fibers of 3 denier sold under the registered trademark Acrilan 1656 were cut into 1 inch staple lengths Examples III to V In these examples the same procedure as described in Example II was followed, except that the fibres were treated with aqueous solutions of potassium permanganate and added to 5.9 litres of Water contained in the trough of different concentrations. All other aspects of the beatof a Clough laboratory beater. A counter-weight of 3% ing process, handsheet formation and tests were as lbs. was placed on the lever arm of the beater and the described in Example II. The physical properties of the clearance between the roll and bedplate was set at 7 mil. handsheets and the concentration of the respective Beating was carried out at 1000 ft./min. peripheral roll aqueous solutions are set out in Table 3 below.

TABLE 3 Potassium Tear Burst Thiek- Tensile Shrinkage Example permanganate Strength Strength ness Strength (percent) concentration (grams) (p.s.i.) (mils) (1bs./in.)

percent III 1 46. 4 35. 7 e. a 16.3 12.1 IV 2. 5 4e. 6 17. 2 8.9 12.4 12.4 V 5 95.2 25.7 7.9 40.3 11.6

s eed for a period of 45 minutes. Handsheets were made b the conventional method using the British Standard Examples VI and VII sheet-making apparatus from which the chromium-plated III h s e p the Same Pmiledure as in Example surfacing plates had been removed on account of sticking. 11 as f llOWfid, except that the fibres were treated, in After being pressed, the handsheets were dried by an accordance With Example for a Period of 15 minutes electric iron set, by a pyrometer, to a temperature of in 1.5 litres of a 2.5 percent aqueous solution of potas- 107 C.i2 C. The sheets were again damped and resmm permanganate maintained at a temperature of 60 dried to ensure complete flatness and stability. Physical While, cording to Example VII, the fibres were strengths of the handsheets were tested on an Elmendorf treated in a solution of the same concentration for a tearing tester, a Mullen bursting strength tester, thickness period of 30 minutes at a temperature of 40 C. All by caliper, tensile strength by a Van der Korput tensile other aspects of the heating process, handsheet formatester and shrinkage percent. The physical properties of tion and tests were as described in Example II. The physithe handsheets are set out in Table 1 below, all the results cal properties of th hand h t are set t i T bl 4 of the tests being corrected to standard substance 70 b l g.s.rn.

TABLE 1 TABLE 4 Tear strength 14.3 e r B rst Thick- Tensile Shrinkage Burst strength (p.s.i.) Example ag y (percent) Thickness (mils) Tensile strength (lbs/in.) ViiIIIIIIII Si it? 313 iii 125 Shrinkage percent 15.6

Example H Example VIII In this example 100 grams dry Weight undried acrylo- 100 grams i Welght undned aclylomtnle g i nitrile polymer fibers of 3 denier and of the same composifibre.s of 3 demer Sold imder i reglstered trahemard tion as those employed in carrying out the preceding Acman 1.656 W cu} Into 1 Inch stap 1e lengt S an examples, but which had been stretched to the extent of rapldly surfed i hues of a 2 Pal-Pent. aqueous solu' 29 percent greater than those fibres and referred to as tion of Postassmj permanganate Enamtamed at type I were cut to 1 inch staple lengths and subjected perilture of on an elecmc hot-plate A terha to precisely the same treatment and tests as in Example period of five mmutes the solution was decanted and t e I. The physical properties of the handsheets Produced are fibres were washed free of Potaslum permanganate m set outinTableSbelow water at a temperature of 50-60 C. The fibres were then s spin-dried in a nylon net bag, thereafter air-dried and TABLE 5 laced in a Clough labor ry The heating and Tear strength (grams) 1. 89.4 sheet-forming steps were identical t those described in Burst strength (p s.i,) 10.6 Example I and the test carried out on the resulting hand- Thickness (mils) 93 sheets were the same as h se described in Example Tensile strength (1bs./in.) 17 The physical properties of the handsheets Producfid are percent set out in Table 2 below.

TABLE 2 Example IX In this example the same quantity of the I type fibres Tear strength (grams) 21-2 used in Example VIII were treated with a 2 percent aque- Burst strength (p.s.i.) ous solution of potassium permanganate maintained at a Thickness (mils) 6-9 temperature of 100 C. for a period of five minutes and Tensile strength (lbs/in.) 30-1 thereafter subjected to the beating and sheet-forming steps Shrinkage percent 14.2 described in Example 1, except that after a period of 15 minutes beating was discontinued as it was found that the fibres were fully split into sub-deniers. The physical properties of the handsheets are set out in Table 6 below.

In these examples the same procedure as described in Example II was followed, except that the fibres were treated with aqueous solutions of sodium hypochlorite of TABLE 10 Tear strength (grams) 30.2 Burst strength (p.s.i 4.9 Thickness (mils) 8.0 Tensile strength (lbs/in.) 5.0 Shrinkage percent 9.0

Example XVIII In this example the same procedure as described in Example II was followed, except that the fibres were treated for a period of 5 minutes at a temperature of different concentrations. All other aspects of the beating 100:) m 5 hues of a 2 percent aqueous soiunon of process, handsheet formation and tests were as described Sodmm Perborate' other aspects of the beefing in Example II. The physical properties of the handsheets ess, handsheet formation and tests were as described 1n and the concentration of the respective aqueous solutions Example The Phi/S16E11 P p 0f the handsheets ar s t t i T bl 7 b l are set out in Table 11 below.

TABLE 7 Sodium Tear Burst Thick- Tensile Shrink- Example hypochlorlte Strength Strength ness Strength ge concentration (grams) (p.s.i.) (mils) (lbs/in.) (percent) (percent) X 0.5 87.6 12.2 8.3 8.2 12.1 XI 1.0 54.5 7.5 8.3 9.8 10.7 XII 1. 5 74 7. 9 s. t 9. 5 10.6

Example XIII TABLE 11 In this example the same procedure as described in Tear strength (grams) 35.0 Example 11 was followed, except that the fibres were Burst strength (p.s.i 7.5 treated for a period of 15 minutes in 1.5 litres of a 1.5 Thickness (mils) 7.9 percent aqueous solution of sodium hypochlorite main- Tensile strength (lbs/in.) 5.0 aimed at a temperature of 80 C. followed by soaking for Shrinkage percent 9.0 a period of 15 minutes at a temperature of 20 C. in a 5 percent aqueous solution of sodium sulphite. All other Examp XIX aspects of the beating process, handsheet formation and tests were as described in Example 11. The physical In thls example the sauna Procedure as descntmd properties of the handsheets are set out in Table 8 below. Exampla H was followed, mfcept that the fibres Wgre treated for a period of 15 minutes at a temperature of TABLE 8 100 C. in 5 litres of a 2 percent aqueous solution of strength (grams) 355 potassium persulphate. All other aspects of the beating Burst Strength (psi 5 9 process, handsheet formation and tests were as described Thickness (mils) 73 r in Example II. The physical properties of the handsheets Tensile strength (lbs./in.) 5.7 are Set OutihTable 12 below- Shrinkage percent 10.75

Examples XIV to XVI TABLE 12 In these examples the same procedure as described in Tear strength grams 11.5 Example 11 was followed, except that the fibres were Burst strength p.s.i 12.3 treated for a. period of 5 minutes at a temperature of Thickness mils 7.9 100 C. in 1.5 litres of aqueous solutions of ammonium Tensile strength 1bs./in 11.8 persulphate of different concentrations. All other aspects Shrinkage percent 10.5 of the heating process, handsheet formation and tests V were as described in Example II. The physical properties From the above tables it will be seen that the physical of the handsheets and the concentration of the respective properties of the handsheets prepared from fibers which aqueous solutions are set out in Table 9 below. had undergone treatment with an oxygen-forming agent TABLE 9 Amonium Tear Burst Thick- Tensile Shrink- Example persulphate Strength Strength ness Strength age concentration (grams) (p.s.i.) (mils) (lbs/in.) (percent) (percent) XIV 2 45. 2 8. 0 8.1 5. 5 10 XV 5 53. 0 8.6 7. 9 5. 6 10 XVI 8 s3. 6 20. 0 7. 3 1s. 1 10 Example XVII in accordance with the invention as described in Examples II to VII and IX to XIX were superior to the physical n t xampl the Same Procedure 35 described in properties of the handsheets prepared in accordance with Example II Was followed, eXCePt that the fibres Were Examples I and VIII where the fibers were not subjected treated 01 a period Of 5 minutes at a. temperature Of to treatment with an xygen-forming agent in 5 litres of a 2 Pereent aqueous Solution f It will be understood that although the foregoing ex- Petasshlm 'hiehfema'fe- All other aspects of the t g amples describe some of the more specific details of the P handsheet formation and tests were as described invention, they are given merely for the purposes of illusin Example II. The physical properties of the handsheets tration and the invention is not limited thereto. Thus, alare set out in Table 10 below. though in the examples the invention has been described in connection with the preparation of handsheets, it is applicable to the continuous production of paper sheets or webs of indefinite lengths by conventional means.

The concentration of the aqueous solution of the oxygen-forming agent can be varied to suit particular requirements and may range from /2 percent to 10 percent. Similarly, the temperature of the solution can vary from 10 C. to 100 C. and the time during which the fibres undergo treatment by the solution can be varied as may be found necessary.

We claim:

1. A process for the treatment of fibres formed from an acrylonitrile polymer containing at least 80 percent by weight of acrylonitrile to render said fibres suitable for use in the manufacture of paper comprising the steps of reducing said fibres to staple lengths, immersing said fibres in an aqueous solution consisting essentially of from about .5 percent to 10 percent of an oxygen-forming agent wherein said agent is a member selected from the group consisting essentially of potassium permanganate, sodium hypochlorite, ammonium persulphate, potassium bichromate, sodium perborate and potassium persulphate at a temperature in the range of from 10 C. to 100 C. for 5 to 30 minutes thereby to partially disrupt said fibres, washing said fibres to remove said oxygen-forming agent and drying said fibres.

2. A process for the manufacture of paper from fibres produced from an acrylonitrile polymer containing at least 80 percent by weight of acrylonitrile comprising the steps of reducing said fibres to stape lengths, immersing said fibres in an aqueous solution composed essentially of from about .5 to percent of an oxygen-forming agent wherein said agent is a member selected from the group consisting of potassium permanganate, sodium hypoehloriate, ammonium persulphate, potassium bichromate, sodium perborate and potassium persulphate at a temperature in the range of from 10 C. to 100 C. for 5 to 30 minutes thereby to partially disrupt the fibres, washing said fibres to remove said oxygen-forming agent, drying said fibres, beating said fibres in an aqueous dispersion and forming said fibres into a Web.

3. A process according to claim 1, wherein saidpolymer is a biend of a copolymer of 80 to 99 percent by weight of acrylonitrile and 1 to 20 percent by weight of vinyl acetate and a copolymer of 10 to percent by weight of acrylonitrile and 30 to 90 percent by Weight of a. vinyl-substituted tertiary heterocyclic amine, said blend having an overall vinyl-substituted tertiary heterocyclic amine content of from 2 to 10 percent based on the weight of the blend.

4. A process according to claim 1 wherein said fibres consist of a copolymer of at least percent by weight of acrylonitrile and up to 20 percent by weight of another copolymerizable mono-olefinic monomer. .1

5. A process for the treatment of fibres formed from an acrylonitrile polymer containing at least 80 percent by weight of acrylonitrile according to claim 1.

6. A process for the manufacture of paper from fibres produced from an acrylonitrile polymer containing at leas 80 percent of acrylonitrile according to claim 2.

7. Fibres containing at least 80 percent by weight of acrylonitrile when treated by the process in accordance with claim 1.

8. Paper when produced by the process in accordanc with claim 2.

9. A process according to claim 2 wherein said fibres consist of a copolymer of at least 80 percent by weight of acrylonitrile and up to 20 percent by weight of another copolymerizable mono-olefinic monomer.

References Cited UNITED STATES PATENTS HOWARD R. CAINE, Primary Examiner.

US. Cl. X.R. 

